Belt conveyors which are used for conveying coal, gravel, dirt and the like are typically in the form of an elongated belt which is suspendingly supported by a number of idlers that allow the belt to be smoothly conveyed with materials disposed thereon. Such belt idlers are typically of the type sold under the Limberoller registered trademark. The Limberoller.RTM. troughing idler consists of a steel wire rope that is completely encapsulated in rubber. The elastomer is molded to the rope under heat and pressure so that a sheet of rubber completely covers the rope in the configuration of a molded rubber jacket. Troughing idlers of the Limberoller.RTM. design utilize only two bearings per idler, one bearing being located at each end of the central shaft. The troughing idlers are suspended from the end bearings so as to form a catenary that supports the conveyor belt in a uniform manner. As the belt moves over the idler, the friction between the belt and the rubber causes the idler to revolve on its axis.
While the idlers described above have been used for a number of years to advantageously support belts of belt conveyors, it has been found that the stationary, pivotal bracket mounting assemblies for such Limberollers.RTM. have the disadvantage that they are incapable of giving under the vertical load of materials added to the belt conveyor. More particularly, at a loading location along the belt conveyor, a trough is typically formed by upwardly extending trough side members so as to guide material added to the belt conveyor system toward the center of the belt. The lowermost edges of such trough sides typically have an elastomeric lip or skirt mounted thereto with, for example, a bracket to contain materials loaded onto the belt. The materials are dumped into the trough from another conveyer belt or some other material transporting device and fall therethrough to the belt surface. When the materials are added to the belt in this manner, they are sometimes dropped from a height which is necessarily substantially above the belt and thus the belt conveyor system is exposed to a substantial downward force. Inasmuch as the statically, rotatably mounted Limberollers.RTM. and the like yield only minimally under such vertical loads, repeated loading impacts can damage the rollers and their bearings.
In an effort to minimize the load impact per roller or per bearing assembly, the number of rollers provided per unit length under and adjacent the material adding trough is typically increased several fold so as to distribute the impact stresses of the vertical load. This decreases the likelihood of idler failure. However, increasing the number of rollers is expensive, often structually difficult and does not effectively absorb loading impacts since loading is generally along only a small length of the belt and, thus, only a few idlers can be mounted thereunder.
It would therefore be desirable to mount conveyor belt troughing idlers, at least at the loading trough region of the belt, so that the roller can yield under vertical loads and thereby absorb such loads while maintaining the proper support of the belt and maintaining an effective seal between the belt and the skirt portion of the trough.